This invention relates to a grind rail for skateboards and rollerblades. It relates especially to a knock-down grind rail composed of butted tubular rail sections and to a quick release connection for such butted tubes.
A grind rail is a device or obstacle used by skateboarders to perform various acrobatic feats while on a skateboard. The grind rail consists of a relatively long, relatively large diameter rigid main tube or pipe which is supported by legs at an elevated location above the ground. To use the grind rail, a skateboarder accelerates along the ground toward one end of the grind rail and then leaps up so that the wheels of the skateboard engage the rail adjacent that end and roll along the rail. At any point along the rail, the rider may manipulate the board so that the wheels of the skateboard leave the rail allowing the skateboarder to descend to the ground. The skateboarder may perform various aerial maneuvers, e.g. a reversal flip, before reaching the ground. Rollerbladers also use grind rails.
To facilitate shipping and storing the grind rail, the grind rail may be sold in a knock-down condition. More specifically, the long main tube may be composed of two or more tube sections which are connected together end to end by the ultimate purchaser. Typically, the connection between the adjacent tube sections is made by telescoping the end of one section into the opposing end of the adjacent section and securing the overlapping segments of the two sections by threaded fasteners or the like. This type of connection is disadvantaged in that the edge of the outer tube constitutes a prominent discontinuity in the rolling surface of the grind rail. When the wheels of a skateboard or rollerblade roll over that edge annoying jolts or bumps are communicated to the rider.
Another problem with that type of connection is that the fasteners which are usually in the form of small screws which are screwed into preformed holes in the tube sections. These screws can become lost and their installation requires a tool such as a screwdriver which complicates the assembly of the grind rail. In addition, in some cases, the fasteners may be loosened due to vibrations imparted to the grind rail when in use. On the other hand, corrosion due to prolonged exposure to the weather may make it difficult to remove the fasteners in the event the grind rail has to be knocked down or disassembled for one reason or another. Still further, if the legs of the grind rail rest on uneven ground, the screw holes in the adjacent tube sections may not line up in the rotational direction necessitating the redrilling of the screw holes in at least one of the tube sections.
Accordingly, it is an object of this invention to provide an improved knock down grind rail for skateboards and rollerblades.
A further object of the invention is to provide a grind rail whose rail is composed of sections connected together end to end with no overlap.
Yet another object of the invention is to provide a grind rail of this type which can be assembled and disassembled without any tools.
An additional object of the present invention to provide an improved connection or coupling for connecting tubes together end to end.
Still another object of the invention is to provide a connection for butted tubes which can be made and unmade relatively easily.
Other objects will, in part, be obvious and will, in part, appear hereinafter. The invention accordingly comprises the features of the construction, combination of elements and arrangement of parts which will be exemplified in the following detailed description, and the scope of the invention will be indicated in the claims.
The present knock-down grind rail comprises a rigid main rail composed of a plurality of tube sections whose opposing ends are connected together in abutment. The main rail is supported above the ground by legs extending down from the tube sections.
The connection or coupling that connects the butted ends of the adjacent tubes includes a tubular insert which fits snugly within the opposing ends of the adjacent tubes, bridging the joint between the tubes. Each tube includes a hole for receiving an arm of a special, generally U-shaped clip which releasably couples the two tubes around the insert. The two arms of the clip are joined together outside the tube and are specially shaped so that when the clip is properly seated in the tubes, it draws the two tubes together end to end so that there is essentially no gap between them. Resultantly, the two coupled-together tubes present an essentially continuous cylindrical rolling surface for the wheels of skateboards and rollerblades.
Aside from the two tubes being joined, the connection comprises only two simple parts which are easy to manufacture in quantity. Furthermore, those parts may be assembled to create the connection without requiring any tools at all. Therefore, when the connection is incorporated into a grind rail, it does not add appreciably to the overall cost or complexity of the grind rail. Yet, the connection constitutes a definite marketing advantage because it enables the grind rail to be sold in a knock down condition for easy assembly by the purchaser. Also, while the invention is described in the context of a grind rail, it has equal application to other devices composed of tubes or pipes coupled together in abutment.